Recently, products using a bone conduction technology, which is mounted in a mobile phone to be widely known, have emerged in succession. Various electronic devices, for example, an application product including a speaker or a hearing aid, using the bone conduction technology, have been commercialized. Temuco Japan, which holds the patent related to the bone conduction plans to release a product, such as a speaker and a microphone, which is usable even in a vacuum state and without regard to a usage place, such as underwater, and adopts the bone conduction technology.
In general, vibration of air beats eardrums and the vibration is transferred to cochlea, so that a sound is recognized. On the contrary, the bone conduction directly transmits vibration from a bone to the cochlea. Such a principle enables a user to hear the sound even though the user covers the ears. Accordingly, even though the eardrum has a problem, when the cochlea and the auditory nerve are normal, a person may hear the sound through the bone conduction.
The bone conduction technology itself has been established before, but it is difficult to miniaturize a product adopting the bone conduction technology for commercialization. The reason is that an output by the bone conduction is in proportion to a size of the product. Accordingly, Temuco Japan has invested greatly in developing a bone conduction speaker, in which the number of components is decreased and of which an internal structure is changed. Further, Temuco Japan also has conducted a research on a bone conduction speaker for voice communication, which applies the bone conduction technology.
In general, a sound or vibration output apparatus is an apparatus, such as a speaker, a receiver, a buzzer, a vibration motor (vibrator), outputting a sound or vibration force, which converts an electrical signal input from a signal source into a mechanical signal to output a sound or generate vibration force, and a bone conduction output apparatus also corresponds thereto.
The sound or vibration output apparatus is applied to considerably various fields according to a size and a usage. Particularly, in response to the growth of the information and communication industry, as a small sound or vibration output apparatus, particularly, a small vibration motor, which is widely used for a vibration call of a communication terminal, an application of a linear motion vibration motor, which has a function exceeding a function of an existing rotary vibration motor, is sharply increased according to popularity of a touch screen terminal including a smart phone.
The reason why the linear motion vibration motor is widely applied to a portable IT device, such as a touch phone including a smart phone and a general mobile phone, is a high response speed, small noise, and a greatly improved product life, compared to those of the rotary vibration motor. The response speed means a time taken until vibration force reaches 50% of vibration force in a maximum displacement, which is the biggest reason for the adoption of the linear motion vibration motor.
Recently, a touch screen terminal is evolved to a smart phone and is used by downloading various applications, and the applications perform various functions and demand feedback vibrations in accordance with the functions, and in order to satisfy the demand, there is a demand for a vibration motor having a higher response speed, that is, a higher reaction speed, than that of the linear motion vibration motor in the related art, in the technical field.